In the semiconductor industry, ion implantation systems are typically employed to dope a workpiece with impurities. In such systems, an ion source ionizes a desired dopant element, wherein ions are generally extracted from the ion source in the form of an undifferentiated ion beam. The undifferentiated ion beam is typically directed into a beamline assembly comprising a mass analysis apparatus or mass analyzer, wherein ions of a desired charge-to-mass ratio are selected using magnetic fields. Mass analyzers typically employ a mass analysis magnet (also called an AMU magnet) to create a dipole magnetic field, wherein various ions in an ion beam are deflected via magnetic deflection in an arcuate passageway that effectively separates ions of different charge-to-mass ratios. The mass of an ion relative to the charge thereon (i.e., the charge-to-mass ratio) affects the degree to which it is accelerated both axially and transversely by an electrostatic or magnetic field. Therefore, the selected or desired ion beam can be made very pure, since ions of undesirable molecular weight will be deflected to positions away from the beam. The process of selectively separating ions of desired and undesired charge-to-mass ratios is known as mass analysis.
The selected or desired ions are then directed at a surface of the workpiece positioned in a target chamber or end station, wherein the workpiece, (e.g., a semiconductor substrate or wafer) is generally implanted with the dopant element. Accordingly, the ions of the desired ion beam penetrate the surface of the workpiece to form a region having a desired characteristic, such as a desired electrical conductivity useful in the fabrication of transistor devices. The ions, for example, are embedded into a crystalline lattice of the workpiece material to form the region of desired conductivity, with the energy of the ion beam generally determining the depth of implantation.
The ion beam may be a spot beam (e.g., a pencil beam), wherein the workpiece is mechanically scanned in two dimensions that are generally orthogonal to the generally stationary spot beam; a ribbon beam, wherein the beam is electromagnetically scanned in one direction across the workpiece while the workpiece is mechanically scanned in an orthogonal direction; or an electromagnetically scanned beam that is electromagnetically scanned in two directions across a stationary workpiece. In a typical two-dimensional scan system, for example, a workpiece handling scan arm is associated with the end station(s) in order to translate the workpiece(s) inside a vacuum chamber of the end station. The scan arm typically scans an electrostatic chuck (ESC) that is holding the workpiece through the ion beam, wherein the ESC selectively clamps the workpiece thereto in order to maintain a position of the workpiece with respect to the ESC during processing (e.g., during ion implantation into the workpiece). Various ion implantation processes are designed such that the ESC and workpiece are further rotated about an axis defined perpendicular to the ESC/workpiece plane thru a center of the ESC/workpiece. Accordingly, conventional scan arms may be equipped with a twist head end effector which allows the ESC to be rotated relative to the scan arm.
Conventional twist head end effectors comprise various connections between the rotating and non-rotating components associated with the twist head, wherein the connections permit a rotation of the ESC with respect to the scan arm. The connections provide electrical and fluid coupling of the ESC to the scan arm, wherein electrical power is supplied to the ESC, as well as a provisions for coolant circulation, and, in some cases, conductive gases that are provided to the ESC. Typical twist head end effectors comprise dynamic fluid seals (e.g., sliding seals) for connecting fluid conduits directly to the ESC. Such dynamic fluid seals are typically prone to damage during disassembly and reassembly, and prior twist head end effectors do not typically allow replacement and/or servicing of the ESC or other twist head components without a disassembly of the dynamic fluid seals. Furthermore, typical electrical connections to the ESC comprise ribbon cables between the scan arm and ESC, wherein rotational movement of the ESC with respect to the scan arm is permitted, but limited by the length and/or configuration of the ribbon cables. Such ribbon cables are also prone to wear and may cause particle generation within the ion implantation system. Also, such ribbon cables are typically exposed to sputtering from the ion implantation process, and are exposed to the vacuum environment of the end station, thus leading to increased maintenance intervals.
Thus, it is desirable to provide an apparatus and method for an improved rotary end effector and ESC, wherein ease of removal and remounting of the ESC is significantly improved. It is further desirable that removal and remounting are made possible without disassembly of dynamic fluid seals, and that electrical connections are made such that the electrical connections are robust, are easily maintained, and substantially limit contamination seen in the prior art.